Curvilinear spa shell



FIG. 1 is a top-view of the curvilinear spa shell;

FIG. 2 is a perspective view of the curvilinear spa shell;

FIG. 3 is a side-view of the curvilinear spa shell; and,

FIG. 4 is a bottom view of the curvilinear spa shell.

The broken line drawings in FIGS. 1 and 2 are for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a curvilinear spa shell, as shown and described. 